// THIS IS A BETA! I DON'T RECOMMEND USING IT IN PRODUCTION CODE JUST YET

/*
 * Copyright 2012 Roman Nurik
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.thdev.listviewswipeexample;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ValueAnimator;
import android.annotation.SuppressLint;
import android.graphics.Rect;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AdapterView;
import android.widget.ListView;

/**
 * A {@link android.view.View.OnTouchListener} that makes the list items in a {@link ListView} dismissable. {@link ListView} is given special treatment because by default it handles touches
 * for its list items... i.e. it's in charge of drawing the pressed state (the list selector),
 * handling list item clicks, etc.
 * 
 * <p>
 * After creating the listener, the caller should also call {@link ListView#setOnScrollListener(android.widget.AbsListView.OnScrollListener)}, passing in the scroll listener returned by
 * {@link #makeScrollListener()}. If a scroll listener is already assigned, the caller should still pass scroll changes through to this listener. This will ensure that this
 * {@link SwipeDismissListViewTouchListener} is paused during list view scrolling.
 * </p>
 * 
 * <p>
 * Example usage:
 * </p>
 * 
 * <pre>
 * SwipeDismissListViewTouchListener touchListener =
 *         new SwipeDismissListViewTouchListener(
 *                 listView,
 *                 new SwipeDismissListViewTouchListener.OnDismissCallback() {
 *                     public void onDismiss(ListView listView, int[] reverseSortedPositions) {
 *                         for (int position : reverseSortedPositions) {
 *                             adapter.remove(adapter.getItem(position));
 *                         }
 *                         adapter.notifyDataSetChanged();
 *                     }
 *                 });
 * listView.setOnTouchListener(touchListener);
 * listView.setOnScrollListener(touchListener.makeScrollListener());
 * </pre>
 * 
 * <p>
 * This class Requires API level 12 or later due to use of {@link android.view.ViewPropertyAnimator}.
 * </p>
 * 
 * <p>
 * For a generalized {@link android.view.View.OnTouchListener} that makes any view dismissable, see {@link SwipeDismissTouchListener}.
 * </p>
 * 
 * @see SwipeDismissTouchListener
 */
@SuppressLint("NewApi")
public class SwipeDismissListViewTouchListener implements View.OnTouchListener {
    // Cached ViewConfiguration and system-wide constant values
    private int mSlop;
    private int mMinFlingVelocity;
    private int mMaxFlingVelocity;
    private long mAnimationTime;

    // Fixed properties
    private ListView mListView;
    private OnDismissCallback mCallback;
    private int mViewWidth = 1; // 1 and not 0 to prevent dividing by zero

    // Transient properties
    private List<PendingDismissData> mPendingDismisses = new ArrayList<PendingDismissData>();
    private int mDismissAnimationRefCount = 0;
    private float mDownX;
    private boolean mSwiping;
    private VelocityTracker mVelocityTracker;
    private int mDownPosition;
    private View mDownView;
    private boolean mPaused;

    /**
     * The callback interface used by {@link SwipeDismissListViewTouchListener} to inform its client
     * about a successful dismissal of one or more list item positions.
     */
    public interface OnDismissCallback {
        /**
         * Called when the user has indicated they she would like to dismiss one or more list item
         * positions.
         * 
         * @param listView The originating {@link ListView}.
         * @param reverseSortedPositions An array of positions to dismiss, sorted in descending
         *        order for convenience.
         */
        void onDismiss(ListView listView, int[] reverseSortedPositions);
    }

    /**
     * Constructs a new swipe-to-dismiss touch listener for the given list view.
     * 
     * @param listView The list view whose items should be dismissable.
     * @param callback The callback to trigger when the user has indicated that she would like to
     *        dismiss one or more list items.
     */
    public SwipeDismissListViewTouchListener(ListView listView, OnDismissCallback callback) {
        ViewConfiguration vc = ViewConfiguration.get(listView.getContext());
        mSlop = vc.getScaledTouchSlop();
        mMinFlingVelocity = vc.getScaledMinimumFlingVelocity();
        mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
        mAnimationTime = listView.getContext().getResources().getInteger(
                android.R.integer.config_shortAnimTime);
        mListView = listView;
        mCallback = callback;

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, final View view, final int position, long id) {
                ++mDismissAnimationRefCount;
                view.animate()
                        .translationX(view.getWidth())
                        .alpha(0)
                        .setDuration(mAnimationTime)
                        .setListener(new AnimatorListenerAdapter() {
                            @Override
                            public void onAnimationEnd(Animator animation) {
                                performDismiss(view, position);
                            }
                        });
            }
        });
    }

    /**
     * Enables or disables (pauses or resumes) watching for swipe-to-dismiss gestures.
     * 
     * @param enabled Whether or not to watch for gestures.
     */
    public void setEnabled(boolean enabled) {
        mPaused = !enabled;
    }

    /**
     * Returns an {@link android.widget.AbsListView.OnScrollListener} to be added to the {@link ListView} using {@link ListView#setOnScrollListener(android.widget.AbsListView.OnScrollListener)}.
     * If a scroll listener is already assigned, the caller should still pass scroll changes
     * through to this listener. This will ensure that this {@link SwipeDismissListViewTouchListener} is paused during list view scrolling.</p>
     * 
     * @see {@link SwipeDismissListViewTouchListener}
     */
    public AbsListView.OnScrollListener makeScrollListener() {
        return new AbsListView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(AbsListView absListView, int scrollState) {
                setEnabled(scrollState != AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
            }

            @Override
            public void onScroll(AbsListView absListView, int i, int i1, int i2) {
            }
        };
    }

    @SuppressLint("NewApi")
    @Override
    public boolean onTouch(View view, MotionEvent motionEvent) {
        if(true)return false;
        if (mViewWidth < 2) {
            mViewWidth = mListView.getWidth();
        }

        switch (motionEvent.getActionMasked()) {
        case MotionEvent.ACTION_DOWN: {
            if (mPaused) {
                return false;
            }

            // TODO: ensure this is a finger, and set a flag

            // Find the child view that was touched (perform a hit test)
            Rect rect = new Rect();
            int childCount = mListView.getChildCount();
            int[] listViewCoords = new int[2];
            mListView.getLocationOnScreen(listViewCoords);
            int x = (int) motionEvent.getRawX() - listViewCoords[0];
            int y = (int) motionEvent.getRawY() - listViewCoords[1];
            View child;
            for (int i = 0; i < childCount; i++) {
                child = mListView.getChildAt(i);
                child.getHitRect(rect);
                if (rect.contains(x, y)) {
                    mDownView = child;
                    break;
                }
            }

            if (mDownView != null) {
                mDownX = motionEvent.getRawX();
                mDownPosition = mListView.getPositionForView(mDownView);

                mVelocityTracker = VelocityTracker.obtain();
                mVelocityTracker.addMovement(motionEvent);
            }
            view.onTouchEvent(motionEvent);
            return true;
        }

        case MotionEvent.ACTION_UP: {
            if (mVelocityTracker == null) {
                break;
            }

            float deltaX = motionEvent.getRawX() - mDownX;
            mVelocityTracker.addMovement(motionEvent);
            mVelocityTracker.computeCurrentVelocity(1000);
            float velocityX = Math.abs(mVelocityTracker.getXVelocity());
            float velocityY = Math.abs(mVelocityTracker.getYVelocity());
            boolean dismiss = false;
            boolean dismissRight = false;
            if (Math.abs(deltaX) > mViewWidth / 2) {
                dismiss = true;
                dismissRight = deltaX > 0;
            } else if (mMinFlingVelocity <= velocityX && velocityX <= mMaxFlingVelocity
                    && velocityY < velocityX) {
                dismiss = true;
                dismissRight = mVelocityTracker.getXVelocity() > 0;
            }
            if (dismiss) {
                // dismiss
                final View downView = mDownView; // mDownView gets null'd before animation ends
                final int downPosition = mDownPosition;
                ++mDismissAnimationRefCount;
                mDownView.animate()
                        .translationX(dismissRight ? mViewWidth : -mViewWidth)
                        .alpha(0)
                        .setDuration(mAnimationTime)
                        .setListener(new AnimatorListenerAdapter() {
                            @Override
                            public void onAnimationEnd(Animator animation) {
                                performDismiss(downView, downPosition);
                            }
                        });
            } else {
                // cancel
                mDownView.animate()
                        .translationX(0)
                        .alpha(1)
                        .setDuration(mAnimationTime)
                        .setListener(null);
            }
            mVelocityTracker = null;
            mDownX = 0;
            mDownView = null;
            mDownPosition = ListView.INVALID_POSITION;
            mSwiping = false;
            break;
        }

        case MotionEvent.ACTION_MOVE: {
            if (mVelocityTracker == null || mPaused) {
                break;
            }

            mVelocityTracker.addMovement(motionEvent);
            float deltaX = motionEvent.getRawX() - mDownX;
            if (Math.abs(deltaX) > mSlop) {
                mSwiping = true;
                mListView.requestDisallowInterceptTouchEvent(true);

                // Cancel ListView's touch (un-highlighting the item)
                MotionEvent cancelEvent = MotionEvent.obtain(motionEvent);
                cancelEvent.setAction(MotionEvent.ACTION_CANCEL |
                        (motionEvent.getActionIndex()
                        << MotionEvent.ACTION_POINTER_INDEX_SHIFT));
                mListView.onTouchEvent(cancelEvent);
            }

            if (mSwiping) {
                mDownView.setTranslationX(deltaX);
                mDownView.setAlpha(Math.max(0f, Math.min(1f,
                        1f - 2f * Math.abs(deltaX) / mViewWidth)));
                return true;
            }
            break;
        }
        }
        return false;
    }

    class PendingDismissData implements Comparable<PendingDismissData> {
        public int position;
        public View view;

        public PendingDismissData(int position, View view) {
            this.position = position;
            this.view = view;
        }

        @Override
        public int compareTo(PendingDismissData other) {
            // Sort by descending position
            return other.position - position;
        }
    }

    private void performDismiss(final View dismissView, final int dismissPosition) {
        // Animate the dismissed list item to zero-height and fire the dismiss callback when
        // all dismissed list item animations have completed. This triggers layout on each animation
        // frame; in the future we may want to do something smarter and more performant.

        final ViewGroup.LayoutParams lp = dismissView.getLayoutParams();
        final int originalHeight = dismissView.getHeight();

        ValueAnimator animator = ValueAnimator.ofInt(originalHeight, 1).setDuration(mAnimationTime);

        animator.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                --mDismissAnimationRefCount;
                if (mDismissAnimationRefCount == 0) {
                    // No active animations, process all pending dismisses.
                    // Sort by descending position
                    Collections.sort(mPendingDismisses);

                    int[] dismissPositions = new int[mPendingDismisses.size()];
                    for (int i = mPendingDismisses.size() - 1; i >= 0; i--) {
                        dismissPositions[i] = mPendingDismisses.get(i).position;
                    }
                    mCallback.onDismiss(mListView, dismissPositions);

                    ViewGroup.LayoutParams lp;
                    for (PendingDismissData pendingDismiss : mPendingDismisses) {
                        // Reset view presentation
                        pendingDismiss.view.setAlpha(1f);
                        pendingDismiss.view.setTranslationX(0);
                        lp = pendingDismiss.view.getLayoutParams();
                        lp.height = originalHeight;
                        pendingDismiss.view.setLayoutParams(lp);
                    }

                    mPendingDismisses.clear();
                }
            }
        });

        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator valueAnimator) {
                lp.height = (Integer) valueAnimator.getAnimatedValue();
                dismissView.setLayoutParams(lp);
            }
        });

        mPendingDismisses.add(new PendingDismissData(dismissPosition, dismissView));
        animator.start();
    }
}
